https://www.telegraph.co.uk/finance/newsbysector/industry/11762086/Warning-Chinese-steel-imports-could-be-safety-threat.html

Chinese steel makers sometimes add boron to their products to get a tax rebate as it was classed as an alloy.

When the steel joined by arc welding, boron can make welds more likely to crack, weakening structures.

http://armstrongsteel.com/network/steel-building-insider/foreign-steel-danger-to-american-suppliers/#.W7P-zPZFw5s

Chinese steel – or any foreign steel for that matter – is much more inferior. Engineers from across the country routinely cite the number of impurities in the foreign steel making process, as well as additives that generally make steel weaker. Chinese steel doesn’t go through the rigorous quality control to which American steel is normally subjected. Worse yet, it’s cheap because it might not be structurally sound.

https://www.prosperousamerica.org/award_winning_california_journalist_labels_bay_bridge_dangerous_due_to_chinese_steel

From 2006 to 2013, California’s state transportation agency Caltrans rebuilt the Bay Bridge, California’s second most famous bridge, which connects San Francisco to the Oakland-Berkeley area across San Francisco Bay. The rebuilding project attracted enormous controversy, due to delays, numerous flaws and defects found in the new structure during the rebuilding, many of them due to the controversial decision to use Chinese steel in the famous bridge.

http://media.sacbee.com/static/sinclair/sinclair.jquery/baybridge/index.html

In March 2008, after more than a year of work, hundreds of weld cracks still appeared. Stolarski directed Merrill, the quality contractor, to alert Peter Siegenthaler, the most senior Caltrans manager for what the department called “Team China.” Merrill recommended that production on the bridge deck panels be halted until ZPMC could produce reliable parts.

“Very shortly after that I was told (by Siegenthaler that) I was no longer authorized to write recommendations on state letterhead,” Merrill said at the hearing.

https://www.wired.com/2015/06/mystery-brand-new-bay-bridges-corroded-steel/

Charpy impact tester—it swings into a thing and, on impact, measures how much energy it took to break that thing. In this case, the thing is steel from a new bridge connecting two cities in one of the most seismically active places on the planet. And the steel broke. The flat, glittery inner surfaces show that in its short time holding together the new Bay Bridge, the steel corroded.

https://www.sfgate.com/bayarea/article/Feinstein-Traffic-is-terrible-Build-a-new-bridge-12410794.php